Commit 49bc8beb authored by Christoph Hellwig's avatar Christoph Hellwig
Browse files

ARM/dma-mappіng: don't override ->dma_coherent when set from a bus notifier 



Commit ae626eb9 ("ARM/dma-mapping: use dma-direct unconditionally")
caused a regression on the mvebu platform, wherein devices that are
dma-coherent are marked as dma-noncoherent, because although
mvebu_hwcc_notifier() after that commit still marks then as coherent,
the arm_coherent_dma_ops() function, which is called later, overwrites
this setting, since it is being called from drivers/of/device.c with
coherency parameter determined by of_dma_is_coherent(), and the
device-trees do not declare the 'dma-coherent' property.

Fix this by defaulting never clearing the dma_coherent flag in
arm_coherent_dma_ops().

Fixes: ae626eb9 ("ARM/dma-mapping: use dma-direct unconditionally")
Reported-by: default avatarMarek Behún <kabel@kernel.org>
Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Reviewed-by: default avatarRussell King (Oracle) <rmk+kernel@armlinux.org.uk>
Tested-by: default avatarMarek Behún <kabel@kernel.org>
parent f7f04d19

arch/arm/mm/dma-mapping.c

+10 −2
Original line number Diff line number Diff line
@@ -1769,8 +1769,16 @@ static void arm_teardown_iommu_dma_ops(struct device *dev) { } 
void arch_setup_dma_ops(struct device *dev, u64 dma_base, u64 size,

			const struct iommu_ops *iommu, bool coherent)

{

	dev->archdata.dma_coherent = coherent;

	dev->dma_coherent = coherent;

	/*

	 * Due to legacy code that sets the ->dma_coherent flag from a bus

	 * notifier we can't just assign coherent to the ->dma_coherent flag

	 * here, but instead have to make sure we only set but never clear it

	 * for now.

	 */

	if (coherent) {

		dev->archdata.dma_coherent = true;

		dev->dma_coherent = true;

	}



	/*

	 * Don't override the dma_ops if they have already been set. Ideally